Hi,
I was looking through our MTA logs and I noticed that the MacOS client sends:
HELO smtpclient.apple
when it should be sending:
HELO my.fq.dn
or if it has no meaningful mapping to a domain name, at least:
HELO [192.168.1.19]
Per RFC-2821:
4.1.1.1 Extended HELLO (EHLO) or HELLO (HELO)
These commands are used to identify the SMTP client to the SMTP server. The argument field contains the fully-qualified domain name of the SMTP client if one is available. In situations in which the SMTP client system does not have a meaningful domain name (e.g., when its address is dynamically allocated and no reverse mapping record is available), the client SHOULD send an address literal (see section 4.1.3), optionally followed by information that will help to identify the client system. The SMTP server identifies itself to the SMTP client in the connection greeting reply and in the response to this command.
This seems pretty straightforward; why is the standard not being followed?
Just double-checked: the iOS client does the same.
If they all send the same meaningless string, this makes reading logs that much harder.
Should be trivial to fix.
Thunderbird had a similar bug, but I fixed that 15 years ago.
Why diverge from the standards? SMTP is one of the easier RFC's to implement.
Thanks,
-Philip
